1. Field of the Invention
This invention relates to a catalyst and a process for removing sulfur and metal contaminants from hydrocarbon feedstocks. More particularly, the invention is concerned with a hydrotreating process for removing metal contaminants, such as nickel and vanadium, from petroleum pertroleum crudes and residua.
2. DESCRIPTION OF THE PRIOR ART
Various processes, such as cracking and hydrocracking, are known for the conversion of hydrocarbons to low molecular weight products. The catalytic cracking of petroleum feedstocks is one of the major refining operations employed in the conversion of crude petroleum oils to more desirable fuel products, such as heating oils and high-octane gasoline. In general, crude petroleum oils are separated by distillation into a gas oil portion and a heavy end portion or residuum. The gas oil portion of the crude petroleum oil is then catalytically converted and upgraded to high value fuels, while the heavy ends, such as the 1050.degree. F+ materials, are used as low grade fuel or as asphaltic materials.
Supply and demand considerations have recently provided new incentives for catalytically converting the heavy ends of petroleum crude oils. Unfortunately, the catalytic conversion of crudes or residua which contain relatively large amounts of heavy ends and/or 1050.degree. F+ materials to lower boiling and more useful hydrocarbons presents a particularly difficult problem. This is the case because the so-called residua or heavy ends contain relatively high concentrations of metals, such as nickel and vanadium, which are poisons for many catalyst systems which may be used for the catalytic conversion of these heavy crudes or residua. The present invention relates to an improved catalyst system for removing the metal contaminants from heavy crude oils or residua.